It could be that updates are in the process of installing. Have you attempted to do a restart?
Yes, you may well be right. I restarted and the AntiVirus Plus icon worked first time. I checked for updates and it downloaded but broke off when installing which I gather is a sign that AntiVirus Plus needs a reboot to install an update. After a few retries, the program eventually resumed as normal. I'll keep an eye on it. Thanks
You are quite welcome
Glad that all seems to be okay now.